642978628 has 6 divisors (see below), whose sum is σ = 1125212606. Its totient is φ = 321489312.

The previous prime is 642978619. The next prime is 642978653. The reversal of 642978628 is 826879246.

It can be written as a sum of positive squares in only one way, i.e., 632623104 + 10355524 = 25152^2 + 3218^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80372325 + ... + 80372332.

Almost surely, 2^642978628 is an apocalyptic number.

It is an amenable number.

642978628 is a deficient number, since it is larger than the sum of its proper divisors (482233978).

642978628 is a wasteful number, since it uses less digits than its factorization.

642978628 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 160744661 (or 160744659 counting only the distinct ones).

The product of its digits is 2322432, while the sum is 52.

The square root of 642978628 is about 25357.0232480076. The cubic root of 642978628 is about 863.1087363498.

The spelling of 642978628 in words is "six hundred forty-two million, nine hundred seventy-eight thousand, six hundred twenty-eight".